[RFI] Investigating receive noise - got a few questions

[Dave Cole (NK7Z)]

Hi Andy,

If you can, build a loop, and DF the source.  Use the null to pin down 
the direction.  That will help a lot.  Triangulate on it, and that will 
get you close.  Once close, see if you can hear the RFI on a VHF AM 
receiver.  If so, get a three element beam, and start hunting.

Once you locate the source, you may want to contact the person living 
there, in the kindest of ways, and ask if you can verify the RFI is 
coming from his/her home.

I always have a second ham with me when I contact an RFI source, but in 
Oregon, where pot is legal, 80% of the RFI not caused in my own shack, 
is related to grow lights, so I am cautions.

73s and thanks,
Dave (NK7Z/NNR0DC)
https://www.nk7z.net
ARRL Technical Specialist
ARRL Volunteer Examiner
ARRL OOC for Oregon

On 11/10/18 1:57 PM, Andy KU7T wrote:
> Hi,
> I am trying to sort out receive noise issues with my Flex.
> 
> I am not exactly sure how clean the spectrum could/should be. I have the feeling that I may be more concerned about this just because I can see the spectrum.  I am in an residenial area with 5 acre lots, with miles to the next town and businesses. I always throught/hoped I have no noise issues.
> 
> I took some time last night to turn off all breakers, one after another, until only the shack was left. Then I reduced everything in the shack so the only thing left was the 12V power supply, radio, computer and monitor.  I also adjusted the noise offset on the Alinco Powersupply with no changes, turned off the computer, and unplugged it. At this point any wall warts, modems, routers, etc were also  off. Still no significant changes.
> 
> Take a look here at my spectrum, recorded while I turned off a breaker every 30 s. There is no difference between beginning and the end: https://1drv.ms/v/s!AiAwh4TnZjYMhtoFCHwTeJdHO2MFGw
> 
> I really have not found any major decreases in hash or noise.  Here are my questions:
> 
>    1.  Do I go right about this at all?  Should I only look at the ham bands instead of looking at the half the HF spectrum?
>    2.  There is quite some pulsing/jumping of noise going on below 10 Mhz (see in video’s top spectrum). Are those normal static atmospheric crashes or something else outside I should be investigating further and if so how?
>    3.  There are patterns around 4 – 5 Mhz that are definitely some patterns from some device. Is it worth worrying about these, considering there are not near any ham bands of interest? Goes back to question 1 also: do I care whats outside of ham bands?
>    4.  I have some harmonics, some spikes between 12 and 15 Mhz. the distance between the spikes is about 17.6khz. Any ideas what that could be? Is likely not in my house though…
> 
> Any tips and ideas how to proceed?
> 
> 73
> Andy
> KU7T
> 
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> 
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